A new study shows that rates of anemia have started to decline. But not for everyone, everywhere. Experts say we need to look at underlying causes.

One in every four people in the world suffer from anemia, where the body lacks enough of the healthy red blood cells that provide oxygen to body tissues.

New research out of the University of Washington in the U.S. city of Seattle found that these numbers are starting to improve, but not for all populations of people. And researchers say real headway won’t be made until the world addresses underlying diseases and societal inequities.

Anemia is a global public health problem. The study measured its prevalence in 204 countries over three decades from 1990 to 2021. It estimates that nearly 2 billion people suffer from the condition.

Anemia is associated with poor health outcomes, increased morbidity and mortality and poor quality of life.

“Even to this day, there is a very large burden due to anemia,” says Will Gardner, research scientist at the Institute of Health Metrics and Evaluation at the University of Washington and lead author of the study. “The burden is particularly concentrated among women and children, groups that have been the focus of international targets and mitigation efforts. We find that the prevalence of anemia in these groups has been fairly stagnant.”

Targeting underlying causes

In May, the World Health Organization released a new framework to address the direct causes, risk factors and social inequities that drive anemia and called for a 50% reduction of anemia rates in women of reproductive age by 2030. The Global Nutrition Target 2022 aims to reduce its prevalence to less than 10% in adolescents, and less than 15% in pregnant women and children under five years by 2030.

“Making anemia less, making anemia better, requires a consideration of who has the condition, where do they live and what are the likely causes,” says Nicholas J. Kassebaum, global health professor at the University of Washington. “Treatment cannot be a one size fits all. It has to be a bit more personalized.”

Anemia causes weakness, fatigue and low concentration in adults, making it challenging to work and go about one’s daily life. In children, it is associated with impaired cognitive and motor development, and increased susceptibility to infectious diseases.

It puts pregnant women at increased risk of preterm labour and postpartum hemorrhage. And it makes the elderly vulnerable to hospitalisation and poor surgical outcomes.

But there is good news: the number of people with the condition fell from about 28% in 1990 to just over 24% in 2021, and there has been a shift toward less severe cases worldwide.

Improved health for some, but not all.

The study, conducted by the Institute of Health Metrics and Evaluation at the University of Washington in Seattle and published in the Lancet Haematology on 31 July, says that despite the declining trend, not much else has changed. Young children, women of reproductive age and countries in sub-Saharan Africa and South Asia remain the most affected.

The study is the most comprehensive effort at estimating the global anemia burden to date. It measures the prevalence of anemia for every age group, gender and according to pregnancy status, as well as its prevalence based on severity and underlying causes.

“Describing the burden of anemia is important,” Kassebaum said. “But if we are going to actually bend the needle, we need to understand what are the likely underlying causes that we need to target.”

Progress in achieving the World Health Organization’s targets has been slow. “Are we likely to achieve the target? No,” says Kassebaum. “Is it realistic to expect and plan for a mechanism so anemia decreases by half? Absolutely.”

The largest decreases were found in adult males. In 2021, across all ages anemia affected 17.5% of men but the numbers for women were almost twice that — 31.2%. The highest prevalence, at 41.4%, was seen in children under the age of five.

The gender and age gap of anemia

The gender discrepancy increases sharply with age, diverging after age five. About 34% of females aged 15 to 49 suffered from anemia in 2021, compared with just about 11% of males. Women also spent more years living with the condition than men.

“Physiological changes in women between 15 and 49 years are large drivers of anemia,” Gardner said. “In some cases, social norms, such as who has access to food, power in the labour market and decisions in agriculture, also drive disparities. Among children, conditions such as malnutrition are not as stratified by sex, and so the divergence is less. In fact, at older ages, there starts to be a bit of reconvergence in anemia rates between men and women.”

The study also shows a large negative association between socio-economic development and anemia, with the difference between the greatest and lowest burden being more than 50%.

The highest prevalence was found in western sub-Saharan Africa, followed by South Asia and central sub-Saharan Africa, the same regions that were the most affected in 1990. By contrast, Australia, Western Europe and high-income North America had the lowest anemia rates.

“The places that had the highest burden have made the least progress,” Kassebaum said. “I think that is a pretty consistent rule, even though some countries in these regions might be independent exceptions.”

Where you are in the world makes a difference.

Socio-economic drivers, such as education, income and lower fertility, all contribute to the high burden in these regions. The fact that these countries also have a confluence of disabling diseases is also a factor.

Gardner notes countries in Central America, Mexico and parts of South America have deployed strategies that have improved anemia rates.

For example, a national Mexican program, known as Prospera, which provides cash payments to poor families in exchange for regular school attendance, health clinic visits and nutrition support, has been associated with decreased anemia prevalence.

Dietary iron deficiency is the leading cause of anemia worldwide. However, only providing iron supplements, which has been the focus of policy initiatives globally, is not sufficient.

The study notes variations in the causes of anemia by age and gender underline the need to address other diseases and conditions that lead to anemia. For people older than 80, chronic kidney disease was the second leading cause of anemia.

Gynecological disorders and maternal hemorrhage increased the risk of anemia in women of reproductive age. Among children younger than five, haemoglobinopathies, malaria and other infectious diseases were important contributors in locations where these diseases are prevalent.

In some cases, providing iron supplements without addressing underlying causes can be harmful.

Kassebaum gives this example: In areas with intense malaria transmission, giving iron supplements to children without treating or preventing malaria led to an increase in the severity of the disease, a greater number of cases and higher mortality.

“While iron supplementation is a key part of any strategy globally, it should be paired with other interventions that are likely to make supplementation programs more effective,” Gardner said. 

Questions to consider:

1. 1. Why are children and women affected by anemia more than men?
   2. Which regions of the world are most affected by anemia and why?
   3. Consider the foods you eat. Do you think you get enough iron in your diet and if not, how could you change that?

Shefali Malhotra is a health policy researcher based in New Delhi and a graduate of the fellowship in global journalism at the Dalla Lana School of Public Health, University of Toronto. 

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